NAME
time —
time command execution
SYNOPSIS
time |
[-clp] command
[argument ...] |
DESCRIPTION
Thetime utility executes and times
command. After the command finishes,
time writes the total elapsed time (wall clock time),
(“real”), the CPU time spent executing
command at user level (“user”), and the
CPU time spent executing in the operating system kernel (“sys”),
to the standard error stream. Times are reported in seconds.
Available options:
-c- Displays information in the format used by the
timebuiltin of csh(1). -l- Lists resource utilization information. The contents of the command process's rusage structure are printed; see below.
-p- The output is formatted as specified by IEEE Std 1003.2-1992 (“POSIX.2”).
Some shells, such as
csh(1) and ksh(1), have their own and syntactically different built-in
version of time. The utility described here is
available as /usr/bin/time to users of these
shells.
Resource Utilization
If the -l option is given, the following
resource usage information is displayed in addition to the timing
information:
- maximum resident set size
- average shared memory size
- average unshared data size
- average unshared stack size
- page reclaims
- page faults
- swaps
- block input operations
- block output operations
- messages sent
- messages received
- signals received
- voluntary context switches
- involuntary context switches
FILES
- ⟨sys/resource.h⟩
EXIT STATUS
The time utility exits with one of the
following values:
- 1-125
- An error occurred in the
timeutility. - 126
- The command was found but could not be invoked.
- 127
- The command could not be found.
Otherwise, the exit status of time will be
that of command.
SEE ALSO
STANDARDS
The time utility conforms to
IEEE Std 1003.2-1992 (“POSIX.2”).
BUGS
The granularity of seconds on microprocessors is crude and can result in times being reported for CPU usage which are too large by a second.